1. Field of the Invention
This invention relates to an input device, and more particularly to an input device that allows handwritten characters to be input to a computer by using a magnetic sensor worn by a user on the wrist to measure the locus of a magnet worn by the user on the fingertip as the magnet moves.
2. Description of the Related Art
Various input devices such as a braille keyboard, a mouse, a touch panel, a pen input type touch pad, and an acceleration (or accelerating force) input type pen are known to be used if a visually handicapped person inputs certain data to a computer.
The braille keyboard imposes a heavy burden on people of advanced age because it requires them to learn how the keys are arranged as well as braille. The mouse is difficult for visually handicapped people to operate because in this case, it is impossible to feed back information visually obtained. Further, a mechanical mouse may undergo serious errors owing to sliding of a ball. On the other hand, an optical mouse requires a writing surface, and may undergo serious errors if the surface is excessively reflective or for other reason. Furthermore, since the user uses the entire hand in holding the mouse, the resulting characters tend to be excessively large. On the other hand, the touch panel requires a panel as a writing surface. Such a panel is too large to carry, and the range of writing is limited to within the area of the panel. The pen input type touch pad requires both pad and pen, does not allow data to be input with one hand, and limits the range of writing to within the area of the pad. The acceleration input type pen requires handwritten characters, which are inherently positional information, to be indirectly input, thereby preventing the loci of the characters from being precisely input. Furthermore, it is difficult to determine the extent of the plane within which the mouse can be operated and the extents of the areas of the touch panel and pen input type touch pad within which data can be input.
Thus, the various input devices previously described are all difficult to operate if the user is blind, i.e. in a non-visual environment. Further, even people with normal, healthy bodies must learn how the keys are arranged and how to operate the equipment if they are of advanced age or are not skilled in operation of electronics. Accordingly, these input devices are not user friendly. Moreover, under these circumstances, substantially no input devices can be used in a mobile environment by visually handicapped people, people of advanced age, or those who are not skilled in operation of electronics (hereinafter simply referred to as “visually handicapped people and others”).
On the other hand, an input device that is easily wearable and that allows handwritten characters to be directly input, if any, is very convenient to visually handicapped people. Such an input device allows a computer to be easily used even in a mobile environment. Studies conducted by the inventor indicate that a magnetic sensor is optimum for implementation of such an input device. However, in this case, detection signals are as weak as geomagnetism, so that the effects of the geomagnetism must be completely eliminated.